I edited my commEnv file and setDomainEnv file and changed every occurance of -Xms256m to -Xms1024m and -Xmx512m to -Xmx2048m but still i am getting the same error. Where am I missing? What other files I may need to edit which AdminServer refers while staring the service through windows service?

Is there any variables or environment variables which I am missing to set? Please help.

4. Attempt to start the service again and it should start successfully. Check the <ServerName>-stdout.txt to make sure the server is up and running.

OR delete the exisitng service and create it again:

1. Delete the existing service from the registry and reboot the server.
2. Edit the $MIDDLEWARE_HOME\wlserver_10.3\server\bin\installSvc.cmd
3. Add "set JAVA_VM=-server", or for JRockit only "set JAVA_VM=-jrockit" at the following section:

Thanks Veeravalli, I did exactly the same. Editing the registry didn't help so I deleted the service from registry and create it again and before that added the following in my installSVC file in the section you mentioned

one of the things I didn't mention though was that when I create the service, I run the installAdmServer_Service.cmd file as "Run as Administrator", only then the service gets installed. Can this be related to the fact that this windows service needs to be run under admin account? or Run as Administrator? I am guessing because I tried various heap sizes and also edited my setDomainEnv.cmd and commEnv.cmd file to use 1024 as heap size it but still didn't work and it is failing may be while loading the class? If that is the case then how to run this services as administrator? Am I missing anything else?

Due to Windowse versions we need to run the dos command as' Run as Administrator' and do this config... I dont think thats an issue.
just in case make sure you have java path set and you are using it during config.

Somehow I was able to get the service started however it has stuck at the following point, it says waiting for multiple events, what events it is waiting for? What can I do to fix this? This is log from my adminserver-stdout.txt file